1. Field of the Invention
The present invention relates to methods and systems for efficient message delivery in a multi-channel uni-directional communications system.
2. Description of the Related Art
Media delivery systems, such as direct broadcast satellite and cable systems, have become commonplace in recent years. A media delivery system is an example of a “uni-directional” system, in that communication is primarily uni-directional.
Media delivery systems are also generally defined as “multi-channel” communications systems, in that a given message may take one or many of several parallel paths from origin to destination. Examples of such multi-channel communications systems include a direct broadcast satellite system with multiple transponders or a cable system with multiple channels in frequency division.
In current direct broadcast satellite systems, a Conditional Access Packet (CAP) data stream is typically used to distribute user-specific messages to receiving devices, such as emails, authorizations and the like. A “message” in this context is any information transmission that has a finite total size, e.g., an email message, but not a continuous audio/video data stream.
However, the distribution of user-specific messages requires the use of a multi-channel message “flood” in order to ensure message deliver to the receiving devices. In such a flood, the system sends all messages, even individually addressed messages, over multiple paths of the system at the same time, because it is not known which path is being “listened to” by the receiving device. Each individually addressed message is tagged with a unique address for the receiving device and then transmitted repeatedly on each channel with each receiving device filtering at least one channel to detect its unique address and hence decode its messages.
However, the CAP data stream has limited bandwidth in a typical direct broadcast satellite system and cannot be increased because of system legacy issues. Thus, there is a need in the art for more efficient message delivery in a multi-channel unidirectional communications system. “Efficiency” in this context is used to mean moving the message reliably from the origin to the destination with the least consumption of channel capacity. The present invention provides such efficiencies, which equate to effective increases in available capacity for new services using the fixed system capacity.